Prometrium ?

So I take Prometrium for 10 days to start a cycle.

I was told to start it at the same time each month. Well, last month I took my first pill on the 7th. This cycle I was on 2.5mg of Femera cd 5-9 and was supposed to ovulate on cd 16 through 19 anywhere between there. I’m on cd 21 with no positive opk. Should I go ahead and take the Prometrium or wait a little bit to see if I did ovulate and just didn’t catch it in time? I had one really close on cd 18 and I used pree seed. Maybe wait a week and test for pregnancy and then if I’m not take the pill?